Senate Republicans on Thursday blocked -- for now -- Chuck Hagel's nomination to lead the Pentagon, marking the first time the chamber has successfully filibustered a Cabinet nominee.

Hagel failed to garner the 60 votes necessary to advance to a final confirmation vote. His nomination is still expected to be taken up at a later date, but Republicans mounted an unprecedented opposition, mostly over demands that the White House provide more information about the Libya terror attack.

Hagel was just shy of clearing the 60-vote bar. The final tally was 58-40, with one senator voting present. For procedural reasons, Democratic Leader Harry Reid switched his vote to "no" at the last minute -- a routine move that allows him to bring up the vote later on.

Some Republicans said Thursday that they would be willing to ultimately allow for an up-or-down vote -- which requires only a simple majority -- once they get more answers on Libya from the administration and once lawmakers return from recess. They return the last week of February.

"There are still questions outstanding," Sen. John McCain, R-Ariz., said on the floor, asking for "sufficient time" to get those answers.